Humoral and cell-mediated immune reactions to varicella zoster (V-Z) virus will be studied in normal and immunocompromised persons. Antibody to V-Z virus will be detected by fluorescent antibody & immune adherence techniques. Cell-mediated immunity will be evaluated by measurement of inactivation of V-Z virus by human peripheral White Blood cells. The types of blood cells(s) capable of reacting to V-Z virus will be identified and the mechanism by which viral inactivation occurs will be investigated (eg. interferon, direct cell-killing etc.) The influence of V-Z antibody and antigen-antibody complexes on V-Z cell-mediated immunity will be studied. An attempt will be made to see whether cell-mediated immunity to V-Z virus (or the lack of it) correlates with disease such as severe varicella or the development of zoster. Passive immunization of high risk susceptible children against varicella will be studied, using immune serum globulin of known V-Z antibody titer. The children involved will be those for whom zoster immune globulin is unavailable. A Serologic survey of antibody to V-Z virus in infants, children & adults will be carried out. BIBLIOGRAPHIC REFERENCES: Gershon, A.A., Steinberg, S. and Smith, M. Cell-Mediated Immunity to Varicella-Zoster Virus Demonstrated by Viral Inactivation with Human Leukocytes. Infection and Immunity. 13:1549-1553, 1976. Gershon, A.A. Herpes Simplex Infection and Varicella and Zoster. Current Pediatric Therapy, Eighth Edition, Jan. 1978. In press.